A compound of Formula (V), chemically known as (2S,5R)-6-benzyloxy-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carboxylic acid, can be used as an intermediate in the synthesis of several antibacterial compounds, such as those disclosed in PCT International Patent Application No PCT/FR01/02418, PCT/US2009/031047, PCT/IB2012/054290 and PCT/IB2012/054296.

The compound of Formula (V) i.e. (2S,5R)-6-benzyloxy-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carboxylic acid is disclosed in International Patent Application No. PCT/FR01/02418. Attempts to prepare this compound indicated that it was unstable and syrupy in nature and decomposed on storage. US Patent Publication No. 20100197928 discloses a procedure to prepare a diastereomeric mixture of (S)-5-benzyloxyamino-piperidin-2-carboxylic acid benzyl ester as an oxalate salt in 50:50 ratio.
Since the compound of Formula (V) is an important intermediate in the synthesis of several antibacterial agents, it was desired to have it exist in a stable form. The present inventors have now surprisingly discovered that a sodium salt of (2S,5R)-6-benzyloxy-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carboxylic acid (compound of Formula (I)) can be prepared and has several advantageous properties, including stability on storage.
